Best Synthetic Fibres Class 8 Notes

The clothes that we wear are made up of fabrics and fabrics are made up of fibres which are obtained from either natural or synthetic fibres. In class 8 we will study Synthetic Fibres and Plastics.

Let us look at the best Synthetic Fibres Class 8 notes.

The main Topics of this Chapter are:-

Monomers and Polymers
Synthetic Fibres and types of Synthetic Fibres
Plastics and types of Plastics
Properties of Thermoplastic
Properties of Thermosetting
Advantages and Disadvantages of Plastics

Monomers and Polymers

What are monomers and Polymers?

Monomers are single-chain molecules that join together to form a large single unit called Polymer.

Polymer comes from two Greek words; poly meaning many and mer meaning part/unit. So, Polymer can be defined as many repeating units.

Examples: Cellulose is a natural polymer of Glucose units (monomer).

What is Polymerization?

The process of converting monomers into polymers is called polymerization.

Synthetic Fibres

What are synthetic fibres?

Synthetic Fibres are fibres (thin threads from which clothes are made) that are prepared by human beings through a number of processes using raw materials of petroleum origin, called petrochemicals.

Types of Synthetic Fibres

The types of synthetic Fibres that we are going to study in this chapter are as follows-

Rayon
Nylon
Polyester
Acrylic

Rayon

Rayon is a synthetic fibre that resembles the properties of Silk. It is called Artificial Silk.

Rayon is obtained from wood pulp by chemically treating it.
It is cheaper than silk and can be dyed in many colours.

Uses of Rayon

Mixed with cotton to make bedsheets
Mixed with wool to make carpets

Nylon

It is the first fully synthetic fibre, developed in the year 1931. It was prepared from coal, water, and air.

Properties of Nylon

Some of the properties of Nylon are-

very strong
Light
Elastic
Lustrous
easily washable

Uses of Nylon

Nylon is used for many articles such as ropes, socks, tents, toothbrushes, car seat belts, sleeping, bags, curtains, parachutes, rock climbing ropes, etc.

Polyester

Polyester is made from monomers called ester. Fabrics made from Polyester are not easily wrinkled.

Polyester is often mixed with other fibres (natural or synthetic) to enhance its properties.

Properties of Polyester

Here is a list of a few important properties of Polyester

crease resistant
good tensile strength
easy to wash and wear
water resistant and easily dries

Uses of Polyester

suits, jackets, shirts, trousers etc.
PET (a form of polyester) is used for making bottles, utensils, etc.
water hoses for firefighting and conveyor belts

What does PET stand for?

PET is a short form of Polyethylene terephthalate. PET is a form of polyester used in the manufacturing of bottles, wires, utensils, etc.

Some common properties of PET are- strong and lightweight, transparent, recyclable, etc.

What are Blended Fibres?

These types of fibres are made by mixing two types of fibres.

For example- Polycot – is a mixture of Polyester and Cotton. Similarly, Polywool is a mixture of Polyester and Wool.

Acrylic

These are the synthetic fibres often used to make winter clothes like sweaters, shawls, etc. Acrylic is made up of Acrylonitrile polymer.

Properties of Acrylic

It resembles wool
good tensile strength
Relatively cheaper than natural wool
wrinkle resistant
resistant to moths
elastic and light in weight

Uses of Acrylic

It is used to make shawls, sweaters, and blankets
as furnishing fabrics and carpets
used to make hair wigs
used for making dresses of toys/dolls

Characteristics of Synthetic Fibres

Let us talk about some of the important characteristics of Synthetic Fibres.

Absorbs Less Water– Compared to natural fibres, synthetic fibres absorbs less water.

Durability– Synthetic fibres are more durable than natural fibres.

Cost– The price of synthetic fibres is not so high, easily available at cheaper rates.

Strength– compared to natural fibres, synthetic fibres has high tensile strength.

Resistivity– Synthetic Fibres are resistant to insects and moths.

Colours– Synthetic fibres are prepared using chemicals so available in a variety of colours.

Advantages and Disadvantages of Synthetic Fibres

Advantages	Disadvantages
Fibres are stretchable	Not easily absorbs sweat
High load-carrying capacity	Non-Biodegradable
Wrinkle free	Can catch fire easily
Cost Effective	Not comfortable to wear in a hot and humid climate
A variety of colours are available	Cheaper Synthetic Fibres can cause skin irritation

Plastics

What are Plastics?

Plastics are polymers obtained by arranging monomers in straight chains or cross-linked chains. Plastic is derived from the greek word Plastikos and the Latin word Plasticus, meaning ‘it can be moulded into different forms or capable of moulding’.

Properties of Plastics

Some of the properties of plastics are-

Non-Reactive
Durability
Cost Effective
Poor Conductor of Heat
Poor Conductors of Electricity

Types of Plastics

Plastics can be broadly categorized into two groups. These types of plastics are grouped on the basis of the arrangement of the monomers, or how the monomers are linked to each other. The two types of Plastics are as follows-

Thermoplastic
Thermosetting Plastics

Thermoplastic

The arrangement of the smallest units, i.e, the monomers is in a straight line. These types of plastics can be easily reshaped or moulded on heating.

Examples– Polythene, PET, PVC

Properties of Thermoplastic

easily remoulded to any shape
becomes soft on heating
Recyclable
Lightweight

Thermosetting

In the thermosets, the arrangement of the monomers is branched and cross-linked. These types of plastics cannot be easily reshaped or moulded on heating.

Examples- Bakelite and Melamine

Properties of Thermosetting

cannot be remoulded
cannot be softened on heating
Non-Recyclable

Important Plastic Properties and Uses

Here is a list of some important plastics and their properties and uses.

Polythene

It is a combination of two words- Poly and Ethene. It is obtained by polymerizing ethene. It is a type of thermoplastic type of plastics.

Properties and Uses of Polythene

Some of the properties of Polythene are- tough and durable

Uses of Polythene- making polythene bags, bottles, packets, waterproof plastic sheets, etc.

PVC (Polyvinyl Chloride)

It is also a type of thermoplastic. Monomer of PVC is Vinyl Chloride.

Properties and Uses of PVC

Properties of PVC are- It is hard and strong but not as flexible as Polyhthene.

Some uses of PVC are- it is used in the manufacturing of pipes, insulations, raincoats, etc.

Bakelite

Bakelite is a thermosetting type of plastic. The monomer of Bakelite is made up of phenol and formaldehyde.

Properties and Uses of Bakelite

Properties of Bakelite: It is hard, tough and poor conductor of heat and electricity.

Uses of Bakelite: Used for making handles of utensils, electrical switches, plugs, etc.

Melamine

Melamine is another type of thermosetting plastic. It is a fire resistant plastic.

Properties and Uses of Melamine

Properties of Melamine: It is also hard, very durable, and versatile in nature.

Uses of Melamine: It is used for making tiles, cups, plates, and other unbreakable kitchenwares. It is used as coating for fire-men uniforms as it is fire resistant.

Teflon

It is a type of synthetic polymer which contains carbon and fluorine. The monomer of teflon is tetrafluroethylene.

Properties and Uses of Teflon

Properties of Teflon: It is oil and water resistant due to its slippery surface. It can also withstand high temperature.

Uses of Teflon: It is used as coating in utensils to give a non-stick surface. Also used in electric irons, etc.

Uses of Plastics

There are many uses for plastics in our day-to-day life. We are highly dependent on the use of plastics. Here is the list of different uses of Plastics-

Packaging Food items
Every article we use is made up of plastics
used for making mugs, buckets
As an insulator
Pipes and water tanks, etc.

Bad Effect of Plastic on the Environment

Plastics have made humans’ life easy in many aspects but at the cost of the environment. Plastics have a bad effect on the environment.

Here is a list of the bad effects of plastic on the environment.

It is non-biodegradable so pollutes soil and the environment.
Blockage of drains and sewers
Burning of plastics produces harmful gases
Kills animals

Steps to Save the Environment from Plastic Waste

We can take several steps to save the environment from the misuse of plastics.

List of Steps to save the environment from Plastics

Minimum Use of Plastics
Do not burn the plastics
Proper disposal of plastics
Use cloth bags instead of plastic bags
Avoid single use plastics like plates, straws, etc

We can follow the 5 R Principle to save the environment.

5 R Principles

Refuse– Refuse everything that is made up of plastics.
Reduce- Minimize the use of plastics.
Reuse- Learn to use it again and again before buying a new one.
Repurpose- If you are not in need, then change or use it in a different way.
Recycle- Plastics can be recycled in recycling factories.

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Synthetic Fibres Class 8 Notes

Introduction